upstream: Request PIN ahead of time for certain FIDO actions

When we know that a particular action will require a PIN, such as
downloading resident keys or generating a verify-required key, request
the PIN before attempting it.

joint work with Pedro Martelletto; ok markus@

OpenBSD-Commit-ID: 863182d38ef075bad1f7d20ca485752a05edb727

diff --git a/ssh-keygen.1 b/ssh-keygen.1
index 7e0558fe194edff28ae67a74f901c1518d622c12..e18fcde0187d2122395aa1a38642563e2912459e 100644 (file)
--- a/ssh-keygen.1
+++ b/ssh-keygen.1
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: ssh-keygen.1,v 1.206 2020/08/27 01:06:18 djm Exp $
+.\"    $OpenBSD: ssh-keygen.1,v 1.207 2020/08/27 01:08:45 djm Exp $
 .\"
 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -382,6 +382,8 @@ The default import format is
 Download resident keys from a FIDO authenticator.
 Public and private key files will be written to the current directory for
 each downloaded key.
+If multiple FIDO authenticators are attached, keys will be downloaded from
+the first touched authenticator.
 .It Fl k
 Generate a KRL file.
 In this mode,

diff --git a/ssh-keygen.c b/ssh-keygen.c
index 1d6234c1c483b57056893ef5997d6c9f6b3797d6..66472427670c51a958298b3bc9eec07036fba880 100644 (file)
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.417 2020/08/27 01:07:51 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.418 2020/08/27 01:08:45 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2984,20 +2984,17 @@ do_download_sk(const char *skprovider, const char *device)
        if (skprovider == NULL)
                fatal("Cannot download keys without provider");
 
-       for (i = 0; i < 2; i++) {
-               if (i == 1) {
-                       pin = read_passphrase("Enter PIN for authenticator: ",
-                           RP_ALLOW_STDIN);
-               }
-               if ((r = sshsk_load_resident(skprovider, device, pin,
-                   &keys, &nkeys)) != 0) {
-                       if (i == 0 && r == SSH_ERR_KEY_WRONG_PASSPHRASE)
-                               continue;
-                       if (pin != NULL)
-                               freezero(pin, strlen(pin));
-                       error("Unable to load resident keys: %s", ssh_err(r));
-                       return -1;
-               }
+       pin = read_passphrase("Enter PIN for authenticator: ", RP_ALLOW_STDIN);
+       if (!quiet) {
+               printf("You may need to touch your authenticator "
+                   "to authorize key download.\n");
+       }
+       if ((r = sshsk_load_resident(skprovider, device, pin,
+           &keys, &nkeys)) != 0) {
+               if (pin != NULL)
+                       freezero(pin, strlen(pin));
+               error("Unable to load resident keys: %s", ssh_err(r));
+               return -1;
        }
        if (nkeys == 0)
                logit("No keys to download");
@@ -3609,9 +3606,15 @@ main(int argc, char **argv)
                        printf("You may need to touch your authenticator "
                            "to authorize key generation.\n");
                }
-               passphrase = NULL;
                if ((attest = sshbuf_new()) == NULL)
                        fatal("sshbuf_new failed");
+               if ((sk_flags &
+                   (SSH_SK_USER_VERIFICATION_REQD|SSH_SK_RESIDENT_KEY))) {
+                       passphrase = read_passphrase("Enter PIN for "
+                           "authenticator: ", RP_ALLOW_STDIN);
+               } else {
+                       passphrase = NULL;
+               }
                for (i = 0 ; ; i++) {
                        fflush(stdout);
                        r = sshsk_enroll(type, sk_provider, sk_device,
@@ -3622,9 +3625,8 @@ main(int argc, char **argv)
                                break;
                        if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
                                fatal("Key enrollment failed: %s", ssh_err(r));
-                       else if (i > 0)
+                       else if (passphrase != NULL) {
                                error("PIN incorrect");
-                       if (passphrase != NULL) {
                                freezero(passphrase, strlen(passphrase));
                                passphrase = NULL;
                        }